Methods for determining the duration of pregnancy and the date of delivery

Many women, after learning that they are ininteresting situation, begin to dream about the day when the child is already born. The exact definition of the timing of pregnancy and childbirth is possible only if the conception occurred in a test tube, that is, in the laboratory. Nevertheless, doctors in all other cases still know how to determine the expected date of birth of a child and they have their own methods.

Is it possible to calculate everything exactly?

Pregnancy test

Determining the duration of pregnancy occurs more oftenbased on ultrasound results or based on the exact date of the last critical days. Despite the fact that modern medicine has moved far ahead - only 4% of children are born on the predicted date, with 96% of the babies appearing a couple of weeks earlier or even a little later than the set day. Why does everything happen this way? Methods of determining the timing of pregnancy and the day of birth can calculate an approximate date, while the duration of pregnancy can vary from thirty-seven to forty-two weeks, and all children who appear in this time interval are considered to be born on time.

Please note that after determining the time limitpregnancy and the date of future birth, it will be correct to believe that the birth of a baby can occur in a period that is counted two weeks before the scheduled time and a week after it. Always remember this and do not worry.

How is the gestation period determined by the last month?

Countdown to the onset of menstruation

How does it all happen? At the initial visit to the obstetrician-gynecologist he will ask when the first day of your last menstruation was. Then the doctor uses the Negele formula to determine the gestation period for the last month. What is this formula? The first day of the last critical days is taken for calculation, it takes three months from it and is added to the received date seven days. If the menstrual cycle is less than twenty-eight days, the difference will be subtracted from the date received (for example, three days if the cycle lasts twenty-five days). If the cycle is longer for a couple of days, then the difference is added to the estimated date of birth.

Is this method accurate?pregnancy on a monthly basis? The technique is applied if a woman regularly keeps a calendar of her menstrual cycle and accurately remembers the date of the beginning and the end of menstruation. However, there are still problems, because in a normal state the pregnancy can last from thirty-eight to forty-two weeks, because there will be inaccuracy. Still it is worth noting that the method works only when the future mother does not have problems with the cycle. It should be stable, uniform and last exactly 28 days. In such situations, pregnancy is most likely to last 280 days or, if expressed in the medical language, ten obstetric months, starting from the first day of the last menstrual period.

We determine pregnancy by ovulation

Pregnant girl holding her belly

Determining the length of pregnancy before the delay byovulation is quite simple. With a cycle of 28 days, ovulation occurs approximately on the 14th day. By this day, add 38 weeks and that's it. This will be the day of the expected delivery. Is this the exact way? The fact is that in many women the cycle is unstable and has deviations in the smaller or larger side. The interval between menstruation can be 25 days, and can make up 32-33 days. How to determine the day of ovulation? It occurs 14 days before the start of the next menstruation, but these calculations are not always accurate. All due to the fact that a mature egg lives a couple of days, and spermatozoa are able to live inside the female body to five days after sexual intercourse. This method of determining the duration of pregnancy works best if the time interval between sexual acts was at least 6 weeks.

Ultrasound as a method of establishing pregnancy

Pregnant girl at the doctor's reception

How is everything calculated? On the basis of many years of research and observations, special tables were compiled, in which the gestational age is compared with the parameters of the fetus (the distance from the coccyx to the temechka is taken). The circumference of the head, thorax and even the length of the thigh are also taken into account. Is it possible to determine pregnancy in the early stages? Of course, but in such cases the size of the fetal egg is taken.

Is this the exact way? At the moment, this technique is considered the most accurate. The question arises: "At what time of pregnancy to determine the date of delivery is it allowed to use?" Ultrasound should be used for a period of 4 to 13 weeks. In this period of time, the size of the fetus in women does not actually differ, therefore it is possible to determine the duration of pregnancy even within a day. True, do not forget that the later the measurements are taken, the greater the error will be. Consider immediately that in the second and third trimester, the fetus is affected by many factors: heredity, genetics, mother's nutrition and so on. Therefore, the size of the children may differ, and the term of labor can not be set accurately.

Results of the survey for determining the period of pregnancy

As soon as you appear at the doctor on examination,the specialist will try to estimate the size of the pregnant uterus, and in particular the height of the bottom of her womb, in order to determine the duration of pregnancy. Is this method accurate? Experienced doctors are not magicians at all. The size of the uterus and the height of the bottom in most cases depends on the size of the child, the volume of amniotic fluid, the presence of pathologies and so on. The shorter the gestation period, the easier it will be to take measurements and determine the date when the baby will be born.

How to determine the gestation period for the height of the uterine fundus?

Pregnant girl

The definition of the gestational age iswhen examining the uterus. The height of the bottom of the uterus or, in short, the WDM is the distance between the upper area of ​​the pubic articulation and the upper part of the uterine wall that protrudes from the cavity of the small pelvis. When the fetus starts to grow, the uterus will increase accordingly, and starting from the end of the 4th obstetric month or the 16th week, the uterine fundus can already be measured through the anterior abdominal wall. Until that time, the rate of growth of the uterus is determined only by a vaginal examination.

The height of the uterine fundus will be measured at each visit of the doctor, starting from the 16th week. Until then, an approximate determination of the duration of pregnancy is possible by monthly or by any other means.

How does the measurement process occur? The woman lies on the couch, straightens her legs, it is desirable that the bladder is empty. The doctor, as soon as the patient has laid down, conducts measurements of the height of the standing of the bottom of the uterus using a centimeter tape. The study will take no more than a minute, but it will allow to judge the nature of the growth of the baby, its position and the volume of amniotic fluid.

Of course, there are generally accepted values ​​of WDM,which correspond to each term of pregnancy, but it is always necessary to take into account a lot of factors and that this is an individual indicator that can vary within three centimeters.

Always, conducting such an original analysis ondetermination of the gestational age, pay attention to how exactly the increase in WDM is compared with the previous indicator. From the 24th week of pregnancy, VDM will coincide with the period of pregnancy.

If the WDM is below normal, then this may indicate the following factors:

  • there was an error in determining pregnancy in the early stages;
  • the presence of a wide pelvis in large women;
  • delay in fetal development;
  • decreased volumes of amniotic fluid.

If the VDM is more than normal, then this indicates the following:

  • the fruit is very large;
  • multiple pregnancies;
  • the basin of the mother is narrow;
  • the fruit is not positioned correctly;
  • volumes of amniotic fluid are increased.

Also for the control of the fetus, its growth andvolume of amniotic fluid, the abdominal circumference is measured at the level of the navel. The presented indicator directly depends on the personal characteristics of the future mother, the thickness of the subcutaneous fat, therefore the dynamics of the increase in the circumference are taken into account. These parameters allow you to determine the possible weight of the child. To do this, you need to multiply the number of VDM on the coolant. For example, the WDM is 36 centimeters, and the OC is 95 centimeters, then it turns out that the possible weight of the child is approximately 3420 grams. If the parameters of WDM do not match by a period of three centimeters or more, the doctor appoints additional examinations. To conduct ultrasound, doppler and cardiography, and after, on the basis of the results obtained, treatment is prescribed and the tactics of the forthcoming birth are established.

Dependence of the WDM on the timing of pregnancy.

Duration in weeks



Uterus the size of a chicken egg


Uterus by volume with goose egg


The uterus will already be the size of a fist, and its bottom will be at the top edge of the womb


The bottom of the uterus is located at the middle of the distance between the navel and the heart, about six centimeters above the heart


The uterus stretches out the stomach, the bottom is at a distance of twelve centimeters, the fetal movements appear, the heartbeat is tapped

Twenty four

The bottom of the uterus is located at the level of the umbilicus, this is about twenty-four centimeters above the womb.

Twenty eight

The bottom of the uterus is four centimeters above the navel, the distance above the womb has already increased to twenty-eight centimeters

Thirty two

The uterine base is already in the middle position between the umbilicus andthe approximate distance to the womb is already thirty centimeters, the abdominal circumference at the navel level is equal to eighty centimeters, the navel is smoothed

Thirty six

The bottom of the uterus is located in the same position as the xiphoid process, the abdomen volume has already grown to ninety centimeters, the navel is smoothed


The bottom of the uterus descends in the middle between the xiphoid process and the navel, the distance to the womb is equal to thirty-two centimeters, the abdominal circumference is ninety-six centimeters, the navel is bulging

We set the gestational age by the date of the first movement

How is this method of determining the termpregnancy? It is believed that when the baby is first born, the woman is able to feel the fetus moving about the twentieth week. If a woman has a second pregnancy, then the date of the first movements may come earlier - at about the eighteenth week. Remember this day and just add to it twenty or twenty-two weeks. This will be the approximate date of birth.

How accurate is this method of determiningpregnancy, gender and term of delivery? Some mothers claim that they could feel their child on the seventeenth or even the fifteenth week. This may well be erroneous sensations (the perturbations can easily be confused in this state with intestinal peristalsis), but this may correspond to reality. Still it is necessary to consider, that thin women with high sensitivity recognize movement of the child before full ladies. Much affects the place of attachment of the placenta, if it is located on the front wall, it will prevent the mother from feeling the movement of the baby, while the fetus can be very active or otherwise inactive. The error in a couple of weeks when setting the date of delivery is not uncommon.

Are all methods accurate?

The girl is nauseous

If you apply all methods in practicethe definition of pregnancy in early pregnancy, to set the date of birth, then still prepare for surprises. Approximately 40% (if not less) of children are born on time (on the fortieth week), the other kids are not so "punctual". A child may hurry to appear in the world, but may on the contrary stay in the mother's belly. Therefore, when the thirty-eighth week comes, the future mother should be ready at any moment to go to the hospital.

Are there any popular methods for establishing pregnancy?

Beautiful pregnant girl by the window

Folk methods for determining pregnancy at theearly terms also allow women to learn about their situation. At the same time, of course, it does not matter whether you thought about having a child or have already dropped your hands and did not expect a miracle to happen.

Many years ago, representatives of the beautifulsex also attempted to define pregnancy in the early stages, and each nation had its own methods. Jewish women walked barefoot on the tall grass, and the remaining tracks "told" about whether the girl is in an interesting position or not. The Egyptians gave women a special drink, if they vomited, then the pregnancy was confirmed.

Now women do not differ much from beautifulladies of antiquity, but the technology has gone far ahead, and now it is easier and easier to establish a pregnancy. However, even now many girls want to know faster the result, because they resort to popular methods. These methods were used by our great-grandmothers, but nobody will answer for their reliability today.

  • An old pregnancy test. The test did not always look the same as it is now, but tried to do something similar on the usual test strips. The main component was urine, and iodine was used to determine the interesting situation. You can also use any capacity or paper. If iodine drops into the urine tank and the droplet remains on the surface, then the pregnancy is confirmed. If the paper strip is soaked in the urine and the iodine is dripped onto it, then when the color changes to blue, the result is a negative, lilac or purple color - positive.
  • The color of urine plays a big role. In early terms, they say that urine is dark yellow and very concentrated. It is rumored that such urine is a good influence on the growth of flowers and if you pour it in the garden and wait, you will see the result. They will become more magnificent and beautiful - this is a sign of pregnancy, nothing will change - the result is negative.
  • Sorry for the plants? You can weld the urine in a metal bowl and after boiling place the product in a glass container. During pregnancy, you will see flakes precipitating. The technique is very popular, many women have tried to determine their pregnancy in such an unusual way.

Should I trust people's methods?

The methods are very interesting, but they neverwill give 100% of the result, in contrast to the modern pregnancy test. If you want, of course, you can try on yourself one of the ways to establish a pregnancy, to check its effectiveness or just for the sake of interest. This is an exciting activity, but still use the proven modern methods for the guarantee. If pregnancy is confirmed, then do not hesitate to contact your doctor.

Why should women understand that the term of birth will be approximate?

The thing is that the woman will be psychologicallyset up for a certain date of delivery, and if at the specified time there will be no fights, then she can develop a great deal of stress. This will lead to panic, fear for the baby, anxiety due to a premature or premature pregnancy. Some women even attempted to provoke childbirth, of course, without the participation of a doctor. This can not be done ever. Early hospitalization will not bring positive emotions to anyone, but especially the future mother.

Therefore, all women who are going to give birthchildren, you should immediately remember - the date that is determined by the doctor at the examination or according to the US, approximate (presumed). Deviations are possible in any direction for up to a couple of weeks.

Believe me, it is better for a child to "know" when to himit is necessary to be born, therefore, in normal pregnancy, just trust your body and do not worry about it, swim with the flow and everything will be fine.

When determining the likely week, during thewhich will begin birth, you can be mentally and financially prepared for a trip to the hospital. After all, when the fights begin, you will not be at all until this. The prospective date will allow you to collect all the necessary things for yourself and the future child, to prepare mentally for the birth, because this process is difficult and painful for every woman.

The main thing do not worry, births that started earlier or late for a few days are likely to be delivered at the right time.

Cast off the excitement

When you are preparing for childbirth, then excitement is avoidedwill be almost impossible. Therefore, do not worry at least for the supposed date of delivery, trust your child and let everything go on as usual. Stress on the last days of pregnancy will be and so much, do not add yourself something else and worry just like that. It is better to spend time with advantage, to study materials on education of children, to prepare a room for the baby, to prepare bags for departure to the hospital. Do not postpone these cases for the last minute, otherwise you can forget something, do not have time, and then worry about it already, and the extra stress of the future mother is completely useless.